Re: Square Tube bending

Joe,

The die design depends on "perfect" a bend you need. Can you
tolerate wrinkles on the inside of the bend? If you need a clean
wrinkle free bend you need a mandrel bender which can get fairly
complicated. Basically, the mandrel bender consists of a special
kind of bender which uses an internal mandrel in the shape of the
tube ID to support it at the point of bend. I think this type of
bender is called a draw bender as opposed to the more common
compression benders.

Another method is to fill the tube with Cerrobend or similiar low
melting point alloy to support the tube cross section as you bend.
Then the process is more like bending a solid bar and a decent bend
can be done on a plain compression bender. You melt the alloy out
after bending. Obviously not practical for large quantities of
bending.

However you do it, it ain't easy. A good quality bend requires the
tube material to be stretched at the outer radius of the bend and
compressed at the inner radius. Square tube is especially hard
because of the amount of material at the inner and outer radii.
Round tube is easier because it doesn't have as much material needing
stretching and compressing at the extremes of the radii.

Doug

--- In CAD_CAM_EDM_DRO@y..., jvicars@c... wrote:
> Is there anything special about dies for bending Square tubing?
> There seems to be very few people who know anything about bending
> square tubing.
> Anyone know where I can find info on this? I want to build a set
of
> my own dies for one specific project.
>
> Thanks.